Inducibility of Sustained Ventricular Tachycardia in a Closed‐Chest Ovine Model of Myocardial Infarction

Reek, Sven; Bicknell, Jeanette L.; Walcott, Gregory P.; Bishop, Sanford P.; Smith, William M.; Kay, G. Neal; Ideker, Raymond E.

doi:10.1111/j.1540-8159.1999.tb00502.x

Cited by 25 publications

(29 citation statements)

References 20 publications

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“…Ovine infarct, unlike canine models, were chosen because they are predictable and histologically similar to human infarction. 24 Temporary arterial occlusions in ovine models reflect current standard practice of primary percutaneous intervention, resulting in more patchy areas of surviving myocardium with an increase in propensity to VT. 5 Continuous cardiac monitoring was not instituted between procedures, limiting detection of nonfatal arrhythmias. Medical therapy such as β-blockers and angiotensin converter enzyme inhibitors, which affect postinfarct mortality, were also not given in this study.…”

Section: Study Limitationsmentioning

confidence: 99%

Evolution of Ventricular Tachycardia and Its Electrophysiological Substrate Early After Myocardial Infarction

Hsieh

Chia

Huang

et al. 2013

Circ: Arrhythmia and Electrophysiology

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Background— Sudden arrhythmic death after myocardial infarction (MI) is most frequent in the first month. Early programmed ventricular stimulation (within 1 week) post-MI has been able to identify long-term ventricular tachycardia (VT) occurrence. We aimed to determine the timing of development and stabilization of VT circuits after MI and how the evolution of the underlying substrate differs with VT inducibility. Methods and Results— MIs were induced in 36 sheep. The 21 survivors underwent serial electroanatomic mapping and programmed ventricular stimulation. Animals were classified as VT pos (inducible VT) or VT neg (noninducible VT) at day 8. Forty-three percent of MI survivors were VT pos on day 8 (9/21), and all remained inducible on day 100 with 1.5 (1.0–2.0) and 1.0 (1.0–2.0) morphologies per animal on days 8 and 100, respectively. Twelve-lead electrocardiogram matched in 15 of 19 VTs between days 8 and 100. The earliest presystolic ventricular activations during VT circuits were in similar locations at the 2 time points. The 12 VT neg animals remained noninducible on day 100. There was no difference in voltage or velocity substrate with time or inducibility. The area with fractionated signals increased with time and VT inducibility. VT pos animals had more linear regions of slowed conduction forming conducting channels. Conclusions— The inducibility and earliest presystolic endocardial activation sites of VT as well as voltage and velocity substrate on day 8 predicted those on day 100 postinfarct, indicating early formation and stabilization of the arrhythmogenic substrate. VT inducibility was influenced by the distribution of conducting channels and increased complex fractionated signals.

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Section: Study Limitationsmentioning

confidence: 99%

Evolution of Ventricular Tachycardia and Its Electrophysiological Substrate Early After Myocardial Infarction

Hsieh

Chia

Huang

et al. 2013

Circ: Arrhythmia and Electrophysiology

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“…A 0.014-inch coronary angioplasty wire was selectively passed into the homonymous artery (ovine left anterior descending artery equivalent). A 3.0ϫ20 mm coronary angioplasty balloon was deployed midway in the homonymous artery equivalent for 3 hours as described by Reek et al 23 After balloon deflation, each animal was observed on the anesthetic table with full hemodynamic monitoring for 1 hour. After this, all sheaths were removed and the animal recovered and observed for a further 1 to 3 hours, and given analgesia with 0.3 mg IM buprenorphine.…”

Section: Myocardial Infarction Inductionmentioning

confidence: 99%

Comparison of Electroanatomic Contact and Noncontact Mapping of Ventricular Scar in a Postinfarct Ovine Model With Intramural Needle Electrode Recording and Histological Validation

Sivagangabalan

Pouliopoulos

Huang

et al. 2008

Circ: Arrhythmia and Electrophysiology

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Background-Substrate-based ablation is useful for nonhemodynamically tolerated postinfarct ventricular tachycardia. We assessed the accuracy of the CARTO contact and EnSite noncontact systems at identifying scar in a chronic ovine model with intramural plunge needle electrode recording and histological validation. Methods and Results-Scar mapping was performed on 8 male sheep with previous percutaneous-induced myocardial infarction. Up to 20 plunge needles were inserted into the left ventricle of each animal in areas of dense scar, scar border, and normal myocardium. A simultaneous CARTO map and EnSite geometry were acquired using a single catheter, and needle electrode locations were registered. A dynamic substrate map was constructed using ratiometric 50% peak negative voltage. The scar percentage around each needle location was quantified histologically. Analysis was performed on 152 plunge needles and corresponding histological blocks. Spearman correlation with histology was 0.690 (PϽ0.001) for needle electrode peak-to-peak voltage (PPV), 0.362 (PϽ0.001) and 0.492 (PϽ0.001) for CARTO bipolar and unipolar PPV, and 0.381 (PϽ0.001) for EnSite dynamic substrate map (Յ40 mm from array). The area under the receiver operator characteristics curve (Ͻ50% and Ն50% scar) was 0.896 for needle electrode PPV, 0.726 and 0.697 for CARTO bipolar and unipolar PPV, and 0.703 for EnSite dynamic substrate map (Յ40 mm from array). Conclusions-Both the CARTO contact and EnSite noncontact systems were moderately accurate in identifying postinfarct scar when compared with intramural electrodes and confirmed with histology. The EnSite dynamic substrate map was comparable to the CARTO contact bipolar PPV when points Ͼ40 mm from the array were excluded. (Circ Arrhythmia Electrophysiol. 2008;1:363-369.)

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“…Myocardial infarction was induced in 12 Wether sheep (45Ϯ6 kg) with the percutaneous technique described by Reek et al 15 Briefly, anesthesia was induced with intravenous thiopental (15 mg/kg) after premedication with intramuscular xylazine (0.1 mg/kg). The sheep were intubated, and anesthesia was maintained with isoflurane (1% to 3%) in 100% oxygen.…”

Section: Infarct Inductionmentioning

confidence: 99%

Organization of Myocardial Activation During Ventricular Fibrillation After Myocardial Infarction

et al. 2005

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Background-Studies of ventricular fibrillation (VF) in small mammals have revealed localized sustained stationary reentry. However, studies in large mammals with surface mapping techniques have demonstrated only relatively short-lived rotors. The purpose of this study was to identify whether sustained high-frequency activation with low beat-to-beat variability was present at intramural sites in a postinfarct ovine model of VF. Methods and Results-VF was induced in 12 sheep 77Ϯ40 days after anterior myocardial infarction. Electrical activation was recorded with 20 multielectrode transmural plunge needles. Unipolar electrogram frequency content and local cycle duration variability were studied in 30-second recordings beginning 5 seconds after the onset of VF. Higher mean beat frequency was associated with lower SD of the cycle duration intervals (rϭϪ0.91, PϽ0.001). The mean beat frequency and the SD of cycle duration intervals of the highest-frequency electrode were 8.8Ϯ2.0 Hz and 17Ϯ11 ms. In 3 cases, a region with regular activation throughout the recording was identified (SD of the cycle duration interval, 6.0Ϯ0.7 ms). Two of these sites and 67% of all sites with low local cycle duration variability were intramural. They occurred within regions with a high dominant frequency as determined by fast Fourier transform of the unipolar electrogram. Conclusions-Regions with the highest frequency of activation during VF were always associated with a low local cycle duration variability and usually intramural in this chronic infarct model. In a minority of cases, a region of stable, rapid, and very regular activation could be identified. These findings support the hypothesis that relatively stable periodic sources form a component of the mechanism of VF in this model.

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Inducibility of Sustained Ventricular Tachycardia in a Closed‐Chest Ovine Model of Myocardial Infarction

Cited by 25 publications

References 20 publications

Evolution of Ventricular Tachycardia and Its Electrophysiological Substrate Early After Myocardial Infarction

Evolution of Ventricular Tachycardia and Its Electrophysiological Substrate Early After Myocardial Infarction

Comparison of Electroanatomic Contact and Noncontact Mapping of Ventricular Scar in a Postinfarct Ovine Model With Intramural Needle Electrode Recording and Histological Validation

Organization of Myocardial Activation During Ventricular Fibrillation After Myocardial Infarction

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